[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
From: Richard Raustad <RRaustad@xxxxxxxxxxxx>
Date: Thu, 07 Feb 2008 13:26:34 -0500
Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys
Delivered-to: linda@xxxxxxxxxx
Delivered-to: mailing list EnergyPlus_Support@xxxxxxxxxxxxxxx
Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=lima; d=yahoogroups.com; b=nkNtuwMzJHpdlLNTXV0Sn64ZdvFyiex4qfenjGN+5YJbA3FKM2cB2f4UJIQVC3/p5cHHSELFh4MGeJUhH2bdnGLufE2/E+fBXyfCTrgcRvdkOfTDJ9a1hCIzcVxYhCjr;
In-reply-to: <fofi82+mht0@eGroups.com>
List-id: <EnergyPlus_Support.yahoogroups.com>
List-unsubscribe: <mailto:EnergyPlus_Support-unsubscribe@yahoogroups.com>
Mailing-list: list EnergyPlus_Support@xxxxxxxxxxxxxxx; contact EnergyPlus_Support-owner@xxxxxxxxxxxxxxx
Organization: Florida Solar Energy Center
References: <fofi82+mht0@eGroups.com>
Reply-to: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sender: EnergyPlus_Support@xxxxxxxxxxxxxxx
User-agent: Thunderbird 2.0.0.9 (Windows/20071031)

Well, I would rather see a graph, but from what you describe, yes it does..

If you wish, email a graph in the spreadsheet (save it as xls) to:
rraustad@xxxxxxxxxxxx

anarui.oliveira wrote:
>
> Differences go up to 1ºC. Does it fit the behaviour of the problem
> you describe?
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > I have looked at this control issue before. I don't think it's the
> > mixing objects or other zone loads. And your offset from the set
> point
> > should be pretty small. Not to worry, the overall annual energy use
> > should be pretty close. Beside, if you run this building using a
> > different building simulation tool, your likely to get a different
> > answer. And I believe the difference in these answers will be
> greater
> > than the difference in annual energy use due to the set point
> offset. If
> > it happens all the time, adjust your set point so the "average"
> zone
> > temperature is near your target temperature.
> >
> > anarui.oliveira wrote:
> > >
> > > Could the mixing objects or anything like that contribute to this
> > > problem? Or some definitions such as humidity ratios or the
> like?...
> > > Getting worried here... the aim was exactly to predict the energy
> > > consumption of a building throughout a year (for official, legal
> > > purposes)...
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "anarui.oliveira"
> > > <anarui.oliveira@> wrote:
> > >
> > > Is this problem equally likely to happen if I use a Purchased Air
> > > approach?
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > <RRaustad@> wrote:
> > > >
> > > > You could try increasing the time step in hour. I have no other
> > > > suggestions. This is a known issue and we are working to
> correct it.
> > > >
> > > > anarui.oliveira wrote:
> > > > >
> > > > > That field is already set to 1, and time step in hours is set
> to
> > > 4.
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > > > <RRaustad@> wrote:
> > > > > >
> > > > > > What you describe is not a capacity issue, it is related to
> the
> > > > > > prediction of loads. If you add the report variable
> > > for "Zone/Sys
> > > > > > Sensible Load Predicted" and set the report variable
> frequency
> > > to
> > > > > > detailed, you will see why this is happening. Try reducing
> the
> > > > > Minimum
> > > > > > System Time Step in the System Convergence Limits object.
> You
> > > > > probably
> > > > > > will not eliminate the problem, but it should get better.
> > > > > >
> > > > > >
> > > > > > anarui.oliveira wrote:
> > > > > > >
> > > > > > > What if, in a similar (heating) case, water flow doesn't
> > > reach the
> > > > > > > maximum when the problem occurs, and increasing the air
> flow
> > > > > causes
> > > > > > > further departure from temperature setpoint?...(Less than
> > > about
> > > > > 1.5
> > > > > > > times the auto-sized air flow also leads to poorer
> setpoint
> > > > > > > tracking); reported air flow is always equal to the
> constant
> > > > > volume
> > > > > > > fan flow, and ouside air flow rate is (and must be) user
> > > > > specified.
> > > > > > >
> > > > > > > Regards,
> > > > > > > Ana.
> > > > > > >
> > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard
> Raustad
> > > > > > > <RRaustad@> wrote:
> > > > > > > >
> > > > > > > > Then try again to manually size the coil in the problem
> > > zone to
> > > > > > > twice
> > > > > > > > the size reported in the eio file. Also increase the air
> > > flow
> > > > > rate
> > > > > > > for
> > > > > > > > that fan coil unit and fan to twice the autosized
> value. If
> > > > > htis is
> > > > > > > > happening in more than 1 zone, then just pick 1 for now
> to
> > > test
> > > > > > > this out.
> > > > > > > >
> > > > > > > > Then tell me what happens to the maximum zone
> temperature.
> > > Did
> > > > > the
> > > > > > > > maximum zone temperature go down? Also tell me if the
> water
> > > flow
> > > > > > > rate is
> > > > > > > > at a maximum when the zone temperature exceeds the set
> > > point.
> > > > > You
> > > > > > > can
> > > > > > > > report "System Node VolFlowRate" for the coil water
> inlet
> > > node
> > > > > and
> > > > > > > fan
> > > > > > > > coil air inlet node to easily match volumetric flow rate
> > > with
> > > > > your
> > > > > > > inputs.
> > > > > > > >
> > > > > > > > This just sounds like a sizing issue and should be
> easily
> > > > > resolved.
> > > > > > > >
> > > > > > > > anarui.oliveira wrote:
> > > > > > > > >
> > > > > > > > > Apparently, yes, but I set it to autosize (and I
> think I
> > > > > already
> > > > > > > did
> > > > > > > > > a trial with a larger, user-defined, water flow
> rate)...
> > > > > > > > >
> > > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard
> > > Raustad
> > > > > > > > > <RRaustad@> wrote:
> > > > > > > > > >
> > > > > > > > > > I have not looked at your input file, can you tell
> me
> > > if the
> > > > > > > water
> > > > > > > > > mass
> > > > > > > > > > flow rate through the fan coil is at a maximum when
> the
> > > > > cooling
> > > > > > > set
> > > > > > > > > > point is not met?
> > > > > > > > > >
> > > > > > > > > > anarui.oliveira wrote:
> > > > > > > > > > >
> > > > > > > > > > > Please forgive me for insisting, but I DO have
> some
> > > > > urgency on
> > > > > > > > > this
> > > > > > > > > > > one...
> > > > > > > > > > > Again, thanks for any help,
> > > > > > > > > > > Ana.
> > > > > > > > > > >
> > > > > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > > > <mailto:EnergyPlus_Support%
> > > > > > > 40yahoogroups.com>, "anarui.oliveira"
> > > > > > > > > > > <anarui.oliveira@> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Hi again.
> > > > > > > > > > > >
> > > > > > > > > > > > I'm uploading a new file
> (Zone36598_cFancoil_exp),
> > > > > hoping
> > > > > > > that
> > > > > > > > > > > someone
> > > > > > > > > > > > can help me figure out why the cooling setpoints
> > > are not
> > > > > > > being
> > > > > > > > > > > achieved
> > > > > > > > > > > > for all times when the controls are active
> (namely
> > > in
> > > > > Zone
> > > > > > > > > 36598).
> > > > > > > > > > > The
> > > > > > > > > > > > model consists of Fancoil units created with
> Compact
> > > > > HVAC,
> > > > > > > and
> > > > > > > > > then
> > > > > > > > > > > > edited in the expanded file.
> > > > > > > > > > > > I tried several user-defined and sizing
> options, but
> > > > > > > couldn't
> > > > > > > > > solve
> > > > > > > > > > > the
> > > > > > > > > > > > temperature peaks above 25ºC.
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks in advance,
> > > > > > > > > > > > Ana Rui.
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > --
> > > > > > > > > > Richard A. Raustad
> > > > > > > > > > Senior Research Engineer
> > > > > > > > > > Florida Solar Energy Center
> > > > > > > > > > University of Central Florida
> > > > > > > > > > 1679 Clearlake Road
> > > > > > > > > > Cocoa, FL 32922-5703
> > > > > > > > > > Phone: (321) 638-1454
> > > > > > > > > > Fax: (321) 638-1439 or 1010
> > > > > > > > > > Visit our web site at: http://www.fsec.ucf.edu 
> <http://www.fsec.ucf.edu>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>
> > > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>>
> > > > > > > > > >
> > > > > > > > > > UCF - From Promise to Prominence: Celebrating 40
> Years
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > > --
> > > > > > > > Richard A. Raustad
> > > > > > > > Senior Research Engineer
> > > > > > > > Florida Solar Energy Center
> > > > > > > > University of Central Florida
> > > > > > > > 1679 Clearlake Road
> > > > > > > > Cocoa, FL 32922-5703
> > > > > > > > Phone: (321) 638-1454
> > > > > > > > Fax: (321) 638-1439 or 1010
> > > > > > > > Visit our web site at: http://www.fsec.ucf.edu 
> <http://www.fsec.ucf.edu>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>
> > > > > > > >
> > > > > > > > UCF - From Promise to Prominence: Celebrating 40 Years
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > Richard A. Raustad
> > > > > > Senior Research Engineer
> > > > > > Florida Solar Energy Center
> > > > > > University of Central Florida
> > > > > > 1679 Clearlake Road
> > > > > > Cocoa, FL 32922-5703
> > > > > > Phone: (321) 638-1454
> > > > > > Fax: (321) 638-1439 or 1010
> > > > > > Visit our web site at: http://www.fsec.ucf.edu 
> <http://www.fsec.ucf.edu>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu> 
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > > >
> > > > > > UCF - From Promise to Prominence: Celebrating 40 Years
> > > > > >
> > > > >
> > > > >
> > > >
> > > > --
> > > > Richard A. Raustad
> > > > Senior Research Engineer
> > > > Florida Solar Energy Center
> > > > University of Central Florida
> > > > 1679 Clearlake Road
> > > > Cocoa, FL 32922-5703
> > > > Phone: (321) 638-1454
> > > > Fax: (321) 638-1439 or 1010
> > > > Visit our web site at: http://www.fsec.ucf.edu 
> <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > >
> > > > UCF - From Promise to Prominence: Celebrating 40 Years
> > > >
> > >
> > > --- End forwarded message ---
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
>  

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years



The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/

Follow-Ups:
- Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
  - From: Richard Raustad
- Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
  - From: Richard Raustad
- Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
  - From: Richard Raustad

References:
- [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
  - From: anarui.oliveira

Prev by Date: [EnergyPlus_Support] Heat loss through walls?
Next by Date: Re: [EnergyPlus_Support] Heat loss through walls?
Previous by thread: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
Next by thread: Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
Index(es):
- Date
- Thread